Ophthalmology is the branch of medicine which deals with the diseases and surgery of the visual pathways, including the eye, brain, and areas surrounding the eye, such as the lacrimal system and eyelids. The lacrimal apparatus or system is the physiologic system containing the orbital structures for tear production and drainage. It consists of the lacrimal gland, which secretes the tears, and its excretory ducts, which convey the fluid to the surface of the eye and the lacrimal canaliculi, the lacrimal sac, and the nasolacrimal duct, by which the fluid is conveyed into the cavity of the nose.
For certain types of treatment, it may be desirable to implant a medical device, such as a punctal plug, in the patient's ocular punctum, the drainage orifice near the eye, which provides a flow path for tear fluid from the eye to the canalicular lumen. For example, in order to treat dry eye, a punctal plug may be used to block the tear drainage by closing the lumen of the ocular punctum as treatment for the condition. These simple devices provide only the benefit of closing the lumen.
Often topical pharmacological treatments are prescribed in the form of liquid eye drops However, pharmacological treatments may be difficult for the patient to apply or patients may have difficulty in maintaining an accurate time regime for re-applying the drug and maintaining levels. For example, in treating glaucoma, which is typically condition of the elderly, patients may have difficulty with standard therapies that require application of liquid drops.
More recently, researchers and medical companies have identified the probable benefit from inducing an eluting drug into the device such that in contact with the tear fluid, the eluting drug provides a continual dosage of a drug for achieving and maintaining appropriate therapeutic levels. However, typical punctal plugs, once placed, may migrate internally, such as into the canalicular lumen, or externally, such as when it is released or expelled from the punctum. The migration may be caused by patient discomfort, such as by rubbing the eye or by blinking, squinting, blowing the nose, or sneezing.
The information included in this Background section of the specification, including any references cited herein and any description or discussion thereof, is included for technical reference purposes only and is not to be regarded subject matter by which the scope of the invention is to be bound.